10 Inch Bad Sponge Cake

I baked the Gretchens Sponge cake recipe and doubled the ingredients to get to TWO (10in) round pans by putting 40 ounces of batter in each pan. I was so happy for the first 10 minutes in went into the oven.. BUT , then they started getting this crust in the center and it sunken in a little .. What I'm I doing wrong ? Can anyone guide me on this issue?

Thanks for the advice. I actually did some thought to the recipe and I cut the sugar amount and it fix the problem. No nail needed for it to cook threw. I'm learning , plus I only fill the pan half way with batter. Thank you all so much !